--- /dev/null
+/*
+ * NI general-purpose counter example. Makes the counter
+ * do buffered event counting using comedi_command().
+ * Different clock sources can be chosen
+ * with the choose_clock demo. The gate source is
+ * set to PFI1 (which is assumed to already be configured as
+ * an input). The gate source latches the count
+ * into the data stream, and possibly resets it (for
+ * non-cumulative buffered counting).
+ * Part of Comedilib
+ *
+ * Copyright (c) 2007 Frank Mori Hess <fmhess@users.sourceforge.net>
+ *
+ * This file may be freely modified, distributed, and combined with
+ * other software, as long as proper attribution is given in the
+ * source code.
+ */
+/*
+ * Requirements: A board with a National Instruments general-purpose
+ * counter, and comedi driver version 0.7.74 or newer.
+ */
+
+#define _GNU_SOURCE
+
+#include <assert.h>
+#include <stdio.h>
+#include <comedilib.h>
+#include <math.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <getopt.h>
+#include <ctype.h>
+#include "examples.h"
+
+int ni_gpct_configure_buffered_event_counting(comedi_t *device, unsigned subdevice)
+{
+ int retval;
+ lsampl_t counter_mode;
+ static const unsigned gate_pfi_channel = 1;
+ static const unsigned initial_count = 0;
+
+ retval = reset_counter(device, subdevice);
+ if(retval < 0) return retval;
+
+ retval = set_gate_source(device, subdevice, 0, NI_GPCT_PFI_GATE_SELECT(gate_pfi_channel) /*| CR_EDGE*/);
+ if(retval < 0) return retval;
+ retval = set_gate_source(device, subdevice, 1, NI_GPCT_DISABLED_GATE_SELECT | CR_EDGE);
+ if(retval < 0)
+ {
+ fprintf(stderr, "Failed to set second gate source. This is expected for older boards (e-series, etc.)\n"
+ "that don't have a second gate.\n");
+ }
+
+ counter_mode = NI_GPCT_COUNTING_MODE_NORMAL_BITS;
+ // output pulse on terminal count (doesn't really matter for this application)
+ counter_mode |= NI_GPCT_OUTPUT_TC_PULSE_BITS;
+ /* Don't alternate the reload source between the load a and load b registers.*/
+ counter_mode |= NI_GPCT_RELOAD_SOURCE_FIXED_BITS;
+ /* Reload counter on gate. Do not set if you want to do cumulative buffered counting. */
+ counter_mode |= NI_GPCT_LOADING_ON_GATE_BIT;
+ /* Make gate start/stop counting */
+ counter_mode |= NI_GPCT_EDGE_GATE_STARTS_STOPS_BITS;
+ // count up
+ counter_mode |= NI_GPCT_COUNTING_DIRECTION_UP_BITS;
+ // don't stop on terminal count
+ counter_mode |= NI_GPCT_STOP_ON_GATE_BITS;
+ // don't disarm on terminal count or gate signal
+ counter_mode |= NI_GPCT_NO_HARDWARE_DISARM_BITS;
+ retval = set_counter_mode(device, subdevice, counter_mode);
+ if(retval < 0) return retval;
+
+ /* Set initial counter value by writing to channel 0.*/
+ retval = comedi_data_write(device, subdevice, 0, 0, 0, initial_count);
+ /* Set value of "load a" register by writing to channel 1.*/
+ retval = comedi_data_write(device, subdevice, 1, 0, 0, initial_count);
+
+ return 0;
+}
+
+int ni_gpct_send_command(comedi_t *device, unsigned subdevice, unsigned n_counts)
+{
+ comedi_cmd cmd;
+ static const unsigned num_chan = 1;
+ lsampl_t chanlist[num_chan];
+ int retval;
+
+ memset(&cmd, 0, sizeof(cmd));
+ cmd.subdev = subdevice;
+ cmd.flags = 0;
+ cmd.flags |= TRIG_WAKE_EOS;
+ /* Wake up at the end of every scan, reduces latency for slow data streams.
+ Turn off for more efficient throughput. */
+ cmd.flags |= TRIG_WAKE_EOS;
+ cmd.start_src = TRIG_NOW;
+ cmd.start_arg = 0;
+ /* TRIG_OTHER will use the already configured gate source to latch counts. Can also use
+ TRIG_EXT and specify the gate source as the scan_begin_arg */
+ cmd.scan_begin_src = TRIG_OTHER;
+ cmd.scan_begin_arg = 0;
+ cmd.convert_src = TRIG_NOW;
+ cmd.convert_arg = 0;
+ cmd.scan_end_src = TRIG_COUNT;
+ cmd.scan_end_arg = num_chan;
+ cmd.stop_src = TRIG_COUNT;
+ cmd.stop_arg = n_counts;
+ cmd.chanlist = chanlist;
+ cmd.chanlist_len = num_chan;
+ chanlist[0] = 0;
+
+ retval = comedi_command_test(device, &cmd);
+ if(retval)
+ {
+ fprintf(stderr, "comedi_command_test() failed.\n");
+ return -1;
+ }
+ retval = comedi_command(device, &cmd);
+ if(retval)
+ {
+ fprintf(stderr, "comedi_command() failed.\n");
+ return -1;
+ }
+ return 0;
+}
+
+int ni_gpct_read_and_dump_counts(comedi_t *device, const char *device_filename, unsigned subdevice)
+{
+ char subdevice_filename[100];
+ int retval;
+ int fd;
+ static const unsigned buffer_size = 1000;
+ lsampl_t buffer[buffer_size];
+
+ //TODO: allow subdevice file name to be specified as a command-line option (with sensible default)
+#if 0
+ retval = snprintf(subdevice_filename, sizeof(subdevice_filename), "%s_sub%i", device_filename, subdevice);
+ assert(retval < sizeof(subdevice_filename));
+ fd = open(subdevice_filename, O_RDONLY);
+ if(fd < 0)
+ {
+ fprintf(stderr, "error opening subdevice file \"%s\".\n", subdevice_filename);
+ perror("open");
+ return -errno;
+ }
+#endif
+ fd = comedi_fileno(device);
+ retval = read(fd, buffer, buffer_size * sizeof(lsampl_t));
+ while(retval > 0)
+ {
+ unsigned num_counts = retval / sizeof(lsampl_t);
+ unsigned i;
+ for(i = 0; i < num_counts; ++i)
+ {
+ printf("%i\n", buffer[i]);
+ }
+ retval = read(fd, buffer, buffer_size * sizeof(lsampl_t));
+ }
+ if(retval < 0)
+ {
+ fprintf(stderr, "error reading from subdevice file \"%s\".\n", subdevice_filename);
+ perror("read");
+ return -errno;
+ }
+ return 0;
+}
+
+int main(int argc, char *argv[])
+{
+ comedi_t *device;
+ int retval;
+ struct parsed_options options;
+
+ init_parsed_options(&options);
+ parse_options(&options, argc, argv);
+ device = comedi_open(options.filename);
+ if(!device)
+ {
+ comedi_perror(options.filename);
+ exit(-1);
+ }
+ /*FIXME: check that device is counter */
+ printf("Running buffered event counting on subdevice %d.\n", options.subdevice);
+
+ retval = ni_gpct_configure_buffered_event_counting(device, options.subdevice);
+ if(retval < 0) return retval;
+ retval = ni_gpct_send_command(device, options.subdevice, options.n_scan);
+ if(retval < 0) return retval;
+ retval = ni_gpct_read_and_dump_counts(device, options.filename, options.subdevice);
+ if(retval < 0) return retval;
+ return 0;
+}
+